In case that electronic components are mounted on the substrate, it is generally employed that the paste is applied on the substrate and the electronic components are mounted on the portion thereof, and soldered with a reflow or the like, thus mounted. When the paste-like solder is supplied and applied on a prescribed position of the substrate with a prescribed amount, it is necessary to have such processes as the use of dispenser and screen printing, and the specific apparatus is employed in each of the process in many cases. Furthermore, the solder paste contains a low boiling point of organic solvent so that there is a problem to store the paste itself. Accordingly, the solder paste is stored in a sealed state, or cooled state or the like, as necessary.
For example, the patent document 1 discloses a method of mounting electronic components in which the solder paste is filled in the syringe and attached to the dispenser device, then the paste is applied through the dispenser device, then a LED element is mounted by the mounter, and then the reflow treatment is implemented through heating at a nitrogen gas atmosphere. The patent document 2 discloses a method of soldering electronic components on the substrate in which the solder paste is applied on the soldering portion of the substrate through the screen printing or pre-coating or the like, then electronic component is mounted on the portion with the solder applied, then the preheating to melt the flux is implemented, and then the substrate is heated to a temperature that the solder powder is melted. The patent document 3 discloses the doctor blade method, spin-coating method, spray method, screen printing method, ink jet method or the like as the method of applying Ag paste.
In the patent document 1, the solder paste is mounted or applied between the component to be mounted and the metalized layer, and then treated through the reflow so as to be bonded. However, it is necessary that the solder is practically attached to the dispenser device for patterning the solder for example, and then solder paste is applied through the dispenser device. In addition, it is further necessary to improve the bonding strength, and to reduce the impurities contained in the solder paste.
Although the patent document 2 discloses that the solder powder is approximately spherical, and has a plurality of irregularities across the whole surface, and the mean plane roughness Ra measured with the scanning probe microscope (SPM) of the solder powder is within a range of 18 to 100 nm, in order to avoid the dropping of the solder during the reflow treatment with heat, it is necessary to apply the solder by means of the screen printing or pre-coating or the like for patterning the solder.
In the patent document 3, there is a problem that it is necessary to have such a specific device as the doctor blade method, spin-coating method, spray method, screen printing method, ink jet method or the like for applying electrically conductive paste.